1. Field of the Invention
The invention relates to an aluminum nitride material and a member for use in the production of semiconductors.
2. Related Art Statement
An electrostatic chuck system utilizing Johnson-Rahbek effect is useful for the adsorption and retention of semiconductor wafers. In such a system, the volume resistivity of the substrate of the chuck is preferably 108 to 1013 Ω·cm for improved adsorption force and speed of response. It is therefore desirable to control the volume resistivity of the substrate to be within 108 to 1013 Ω·cm in the temperature range intended for use in the development of an electrostatic chuck.
The following methods are known for reducing the volume resistivity of an aluminum nitride sintered body at about 1010 Ω·cm.
(1) The intergranular phase of the sintered body is made interconnected and electrically conductive so as to reduce the volume resistivity. For example, a large amount of titanium nitride is added to aluminum nitride raw material powder to generate an intergranular phase mainly consisting of titanium nitride. The intergranular phase is interconnected. The interconnected intergranular phase may function as a conductive path. Such a method is described in, for example, Japanese patent publication 10-154, 746.
(2) Oxygen is solid soluted in aluminum nitride particles to improve the conductivity. For example, the assignee filed Japanese patent publication 9-315, 867 and disclosed a method of adding a trace amount of yttrium oxide into aluminum nitride having a high purity to control the volume resistivity at room temperature to a value between 108 to 1013 Ω·cm.